The climate is warm and tropical, with temperatures ranging from 22 to 30 °C. Rainfall is heavy due to annual monsoons and measures around 3000 to 3800 mm each year. The vegetation of the Nicobars is typically divided into the coastal mangrove forests and the interior evergreen and deciduous Tropical and subtropical moist broadleaf forests. Additionally, several islands contain extensive inland grasslands, though these are thought to result from human intervention.

As a result of lower sea levels during the ice ages, the Andaman Islands were linked to the Southeast Asian mainland, but it is not believed that the Nicobar Islands ever had a land bridge to the continent. Lower sea levels did link the islands to one another: Great Nicobar and Little Nicobar were linked to each other, and Nancowry, Chaura, Katchall, Trinka, Camorta, and the nearby smaller islands were linked to one another as well.

The earliest extant references to the name "Nicobar" is in the Sri LankanPaliBuddhist chronicles, the Dipavamsa (c. 3rd or 4th century CE) and the Mahavamsa (c. 4th or 5th century), which state that the children of the followers of the legendary founder of the Sri Lankan Kingdom, Vijaya, landed on Naggadipa (the island of the children, from the Pali nagga meaning 'naked').[3] The modern name is likely derived from the Chola dynasty name for the islands, Nakkavaram or 'Puup Pii' (literally, "naked man" in Tamil) which is inscribed on the Thanjavur (Tanjore) inscription of 1050 CE.[4][5][6]Marco Polo (12th-13th century) also referred to this island as 'Necuverann'.

The history of organised European colonisation on the islands began with the Danish East India Company in 1754/56. During this time they were administrated from Tranquebar (in continental Danish India) administrated under the name of Frederiksøerne; missionaries from the Moravian Church Brethren's settlement in Tranquebar attempted a settlement on Nancowry and died in great numbers from disease; the islands were repeatedly abandoned due to outbreaks of malaria: 1784 - 1807/09, 1830–1834 and finally from 1848 gradually for good. Between 1778 and 1783, William Bolts attempted to establish an Austrian colony on the islands on the mistaken assumption that Denmark had abandoned its claims to the islands.[7]

Denmark's presence in the islands ended formally on 16 October 1868 when it sold the rights to the Nicobar Islands to Britain,[7] which in 1869 made them part of British India.

Several islands were heavily damaged with initial reports of islands broken in two or three pieces and coral reefs moved above water. Teressa Island was said to have been split into two pieces and Trinkat Island into three pieces. Some estimates said that the islands were moved as much as 100 feet (30 m) by the earthquake and tilted.

Airport: Car Nicobar CBD/VECX has an airstrip on Car Nicobar Air Force Base of 2717 by 43 meters on the South East coast near Malacca but does not offer commercial service. Great Nicobar has a small airstrip of approximately 1000 meters at Campbell Bay/Tenlaa on its East coast.

Seaport: At least one small shipping dock is located in Campbell Bay on the East coast of Great Nicobar. Car Nicobar has a small dock at its Northern tip near Keating Point and Mus.

Some officials involved in locating the Malaysia Airlines Flight MH370 have said they believe the aircraft may have crashed somewhere in this region.[8][9] and a passenger flying with Saudi Airlines from Jeddah to Kuala Lumpur, claimed she saw an aircraft in the water about an hour after flying over Chennai.[10]

^C Rasanayagam (1926). Ancient Jaffna. Asian Educational Society (reprint). ISBN81-206-0210-2. P53 "Naggadipa, where the children are alleged to have landed, is certainly Nicobars, the Nakkavaram of the Tamils, ...